About Leukemia

Leukemia is a type of cancer that affects the body's white blood cells (WBCs).

Normally, WBCs help fight infection and protect the body against disease. But in leukemia, WBCs turn cancerous and multiply when they shouldn't, resulting in too many abnormal WBCs, which then interfere with the body's ability to function normally.

In acute myeloid leukemia (AML), too many immature white blood cells (called myeloid blasts) are made. These leukemia cells are abnormal and cannot mature into normal white blood cells. This type of leukemia affects 20% of kids with this cancer of the blood cells.

Thanks to advances in therapy and clinical trials, the outlook for kids with AML is promising. With treatment, most are cured.

Causes

The cause of AML is unknown, though doctors know that certain medical conditions can increase a child's risk of getting AML. However, just because a child has a risk factor does not mean that he or she will get AML.

Risks include inherited genetic problems such as Down syndrome, neurofibromatosis type 1, Fanconi anemia, Noonan syndrome, and other inherited bone marrow failure syndromes (IBMFS). In addition, other non-inherited conditions such as preleukemia (also called myelodysplastic syndrome or MDS) and aplastic anemia can increase the risk of AML.

AML is also more common in kids who've been treated with chemotherapy or radiation. In fact, AML is the most common type of secondary cancer in children who have previously undergone cancer treatment.

In addition, a child with an identical twin who was diagnosed with leukemia before age 6 has a 20% to 25% chance of developing AML. Fraternal twins and other siblings of kids with leukemia have two to four times the average risk of developing it, too.

Certain environmental factors can predispose a child to leukemia. For example, exposure to radiation (such as X-rays) prior to birth may trigger the disease in a developing fetus.

Signs and Symptoms

AML is called "acute" because it tends to worsen quickly if left untreated. Chronic blood cancers, like chronic myelogenous leukemia (CML), tend to progress more slowly. However, the symptoms of all types of leukemia are generally the same and include:

• fatigue and weakness
• swollen lymph nodes
• recurrent infections (like bronchitis or tonsillitis)
• fever
• easy bruising or petechiae (tiny red spots on the skin caused by easy bleeding)
• bone and joint pain
• abdominal pain (caused by abnormal blood cells accumulating in organs like the kidneys, liver, and spleen)

Sometimes a child might have painless lumps that can be felt in the lymph nodes of the neck, underarm, or groin area. These lumps of leukemia cells (called chloromas) can develop anywhere in the body.

Diagnosis

The subtypes of AML are classified according to the way the cells look under a microscope. If a doctor suspects leukemia, a child may undergo tests that include:

• Blood tests. Tests such as a complete blood count, liver and kidney function panels, and blood chemistries can give important information about the number of normal blood cells in the body and how well the organs are functioning. The blood cells will also be examined under a microscope to check for abnormal shapes or sizes, and determine which subtype of AML a child has.
• Bone marrow aspiration and biopsy. In this procedure, the doctor inserts a needle into a large bone, usually the hip, and removes a small amount of bone marrow to examine it for abnormal cells.
• Imaging studies. These may include an X-ray, CT scan, MRI, or ultrasound to check for an enlarged spleen or liver, and also to rule out any other possible causes of a child's symptoms.
• Lumbar puncture. Also called a spinal tap, this procedure uses a hollow needle to remove a small amount of cerebrospinal fluid (the fluid surrounding the brain and spinal cord) for examination in a lab.
• Flow cytometry tests. By analyzing the properties of the cancer cells, doctors can determine the type of leukemia a child has. This is important because treatment varies among different types of leukemia.
• Chromosomal tests. By analyzing DNA from blood or bone marrow, doctors can check for the specific genetic changes that identify the various subtypes of AML. This is important because treatments may vary according to subtype.
• Tissue typing or HLA (human leukocyte antigen) typing. If a child needs a stem cell transplant (also called a bone marrow transplant), this test helps doctors find a suitable stem cell donor. It works by comparing the proteins on the surface of a child's blood cells with the proteins on a potential donor's cells. The more "HLA markers" a child and donor share, the greater the chance that a transplant will be successful.

Treatment

Because it can progress so quickly, there is no staging system for AML. Doctors generally characterize the disease as newly diagnosed or in remission.

Treatment is divided into two phases. The goal of the first phase, called induction, is to kill as many cancer cells as possible and achieve remission (a state where there is no evidence of disease in the body). The second phase (called post-remission, consolidation, or continuation therapy) is designed to eliminate any undetectable leukemia cells.

Phases I and II of treatment may include the following therapies alone or in combination:

• Chemotherapy. This is the use of special drugs to kill the cancer cells. Several chemotherapy drugs are often combined to attack the cancer cells in different ways.
• Chemotherapy through lumbar puncture. This procedure, known as intrathecal (IT) chemotherapy, delivers chemotherapy drugs directly to the cerebrospinal fluid, where cancerous cells can collect.
• All-trans retinoic acid (ATRA). This vitamin A treatment is sometimes given alongside chemotherapy to kids with acute promyelocytic leukemia (APL), a subtype of AML.
• Arsenic trioxide. This substance (an inorganic compound) is also used to treat kids with APL.
• Stem cell transplant (also called bone marrow transplant). This procedure involves destroying cancer cells and normal bone marrow and immune system cells with high-dose chemotherapy and then reintroducing healthy donor stem cells into the body. These new stem cells can rebuild a healthy blood supply and immune system.
• Clinical trials. These are research studies that offer promising new treatments that are not yet available to the general public. A child's doctor will decide if a child is a good candidate for a clinical trial.

Coping

Being told that a child has cancer can be a terrifying experience, and the stress of cancer treatment can be overwhelming for any family.

Although you might feel like it at times, you're not alone. To find out about support that may be helpful to you or your child, talk to your doctor or a hospital social worker. Many resources are available to help you get through this difficult time.

Reviewed by: Emi H. Caywood, MD
Date reviewed: March 2012